One of the known techniques for providing a stabilized voltage reference is to employ an avalanche device such as a zener diode having a relatively low voltage tolerance. Such zener diode devices are available, although rather costly, but require a current value having a relatively narrow tolerance. Thus, a relatively expensive adjustable resistor is usually series connected with the zener diode and adjusted to provide the desired current for the zener diode and to control the output voltage. Obviously, such apparatus is expensive, presents a repeatability problem due to resistance value adjustments, and requires inconvenient adjustments. Moreover, the zener diode current is dependent upon the diode voltage rather than the output voltage.
Another known technique for effecting a stabilized voltage reference is to employ a temperature controlled oven. Again, disadvantages such as thermal transients, heat dissipation, and increased package sizes are detrimental to such an approach.